Formation of the radical‐cation of monomer in the photoinduced polymerization of isobutylene in the presence of SnCl4

Abstract Spectra of isobutylene with SnCl 4 were studied at the temperature of 113°K in the dark and under illumination. Radical‐cations of isobutylene are formed by irradiation of the isobutylene–SnCl 4 mixture in n ‐heptane substantially more slowly than in the isobutylene–TiCl 4 mixture. Polymerization of isobutylene occurs after increasing the temperature up to the melting point of this mixture. The yield of polymer depends on the duration of preirradiation, while the molecular weight of polyisobutylene ( M η ) does not depend on the preirradiation of reaction mixture.